Madness - Gli occhi della luna (1971)

Three men flee at night from an asylum. One is taken back, another accidentally falls under a car and dies, but the third manages to lose track and takes refuge in a country house. The next day, a group of boys arrive at the cottage for a party: the man meanwhile has hidden upstairs, and makes sure not to get noticed by the young. But the party soon degenerates when the boys take LSD; when they wake up, they discover that a girl lies lifeless on the ground.